The cost of living in the metropolitan Washington area surged by 1.5 percent in the two months ended in September, the biggest increase since a 1.6 percent rise in prices for the two months ended in January, according to the federal Bureau of Labor Statistics.

Higher clothing prices were a major factor in the increase in the local consumer price index. The increase in the inflation rate in the Washington area was far higher than the 0.9 percent growth nationally during the same two-month period.

On an annual basis, the 1.5 percent change in consumer prices would produce a 12-month inflation rate of 9.5 percent. Since Dec. 1, 1983, however, the cost of living has risen by only 4.7 percent, moderated by a six-month period in which price increases were low.

Washington area prices increased only 0.5 percent for the two months ended in March, 0.2 percent for the two months ended in May, and 0.9 percent for the two months ended in July.

The biggest increases came in costs for housing, clothing and education. Housing costs rose 2.2 percent -- more than double the 1 percent increase in housing prices for the previous two-month period. Higher rents, higher furniture and appliance prices and higher charges for natural gas and electricity all contributed to the increase.

Apparel and upkeep costs rose by 6.2 percent in the area, compared with an increase of 3.9 percent nationally. BLS economist Jesse Thomas said there appeared to be a bigger seasonal swing here than nationally between end-of-summer sales and higher-priced fall items.

The index for other goods and services rose 2.3 percent, reflecting higher tuition and higher prices for cigarettes and toilet goods.